1. Field of the Invention
The present invention relates generally to motor vehicle differential assemblies and more particularly, to a new and novel means for retaining the ends of the drive axle shafts within a differential assembly. The invention is beneficial in instances where clearances between certain moving components of the assembly are very close.
2. Description of Related Art
Motor vehicle differential assemblies have been in common use for many years to allow one motor vehicle wheel on an axle to rotate at a different rate than the other motor vehicle wheel, such as would occur when a motor vehicle is turning, or two tires having different diameters are being used on the same axle.
A typical motor vehicle differential assembly includes a pair of meshing spider and side gears enclosed in a differential case. The case is usually a one-piece unit, having a ring gear bolted to the case. The case is usually made of cast iron. The spider gears, typically made of hardened steel, are held in place by a steel shaft, known as a pinion shaft, which passes through the differential case and the center of the spider gears. The spider gears, also commonly made of hardened steel, mesh with the side gears. When the ring gear and the differential case turn, the spider and side gears also turn. Power flow is through the case, into the spider gears, and on into the side gears. The side gears are splined to a pair of drive axles and transfer power to the drive axles, which in turn transfer power to wheels which drive the vehicle.
Known prior art means for keeping the drive axles firmly engaged within the side gears include C-locks which are received by a circumferential groove provided in the end of the drive axle and which project radially beyond the periphery of the drive axle to contact a nearby face of the side gear. The C-lock requires the arrangement of the spider gears and the side gears to provide a wide enough space between the side gear face and the pinion shaft to achieve adequate button thickness on the end of the drive axle where the groove for the C-lock is provided. Moreover, the C-lock design provides far less than 360xc2x0 frictional contact around the circumference of the axle shaft, thus fails to provide maximum frictional contact about the circumference of the axle shaft due to the open end of the c-shaped ring. Where the spider gear and side gear arrangement does not yield enough space to realize appropriate button thickness, alternate means of retaining the drive axles are required.
Another known retention means makes use of a cam plug and a set of balls mounted within an axially disposed recess at the end of the drive axle. Rotation of the pinion gear shaft moves the cam plugs further into the recess and the balls outwardly into locking engagement with an annular recess within the side gears. The pinion shaft is then secured against rotation by a pin or screw which extends therethrough.
The present invention achieves the same or better results as the above described known retention means using the C-lock, cam plug and balls; but, with both a greatly simplified design and a stronger link between the side gears and the drive shafts.
It is therefore an advantage of the present invention to provide a new and improved means for retention of a drive axle within a motor vehicle differential assembly that reduces or eliminates the stress risers created in the conventional design and reduces or eliminates the counterbore required for the side gears of the convention design.
These advantages are provided by a system and method for securing drive axles of a motor vehicle differential assembly within the central bores in the side gears of the differential assembly with a pair of arcuate retaining elements having a rounded cross section. These elements preferably are formed from a piece of bar stock bent to define a 180xc2x0 half-ring element. The pair of retaining elements is securely held between an arcuate groove formed along the circumference of the axle and a rounded abutment surface provided on the side gear. The arcuate groove and rounded abutment surface reduce stress risers and eliminate the counterbore typically provided in the side gear. Moreover, the pair of retaining elements maximizes the frictional contact by circumscribing the axle by approximately 360xc2x0.
These advantages and other novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.